OT: What type wood between frame rails and truck box?

[BRENT in 10-uh-C]

This is kinda off-topic but I really don't have a good place to ask this type question, so hopefully someone here knows the answer.

We are building a larger 'tow truck' to pull our trailers (-which will be used for hauling Model-As and parts ) and with the purchase of a Class 8 truck, we are now building a 11½ foot box (-see CAD drawing pictured below) that will effectively make this truck into a RV Toterhome. l have seen where a slab of wood is used between the frame rails and the box's steel frame to eliminate squeaking & slippage. Does anyone know what type of wood is typically used for this application? Would Ash (-since I have an abundance of that species at my disposal) be suitable for use in this area??

Thanks in advance!!

.

[Joe K]

Ash is the "King's Wood" coming from the fact in baronial England the ash trees on the king's land could be burned in the "green" state by the serfs - no piles of wood drying around the serf's cabin to reveal he had been "poaching." To burn the kings wood was considered an ultimate revolutionary act - besides keeping yourself warm at the king's expense.

As a wood resistant to decay, it doesn't work so well. Sort of mid-way between Birch (which can rot in a heartbeat) and oak (which rots but the mechanical strength can endure for quite a while.

Black locust is a wood that is environmentally sound AND highly resistant to rot. Grandmother had a stand of black locust from which she allowed me to cut and make a split rail fence. Each tree in that stand grew from the stump of the previous tree at that location - and it was cut perhaps 25 years before. And every stump of those previous trees were still there. As fenceposts black locust is good for 50-60 years in the ground - longer as rails. Black locust machines well in the green state, dries to tougher than ironwood, the only fault for dimension structures would be change in dimension during drying.

I might tend to use pressure treated lumber for this application. The usual source for pressure treated is southern yellow pine - which is NOT a hardwood, but will take on the biocide chemicals well. For a while pressure treated lumber/plywood was used in substitute for poured concrete foundations for houses - although the recent change in chemicals may have put this on hold.

The chemical in pressure treated USED to be Copper Arsenate - now being done with copper borate I believe which is less effective as a biocide, but more forgiving to the environment. Most pressure treated lumber comes "rated" for various degrees of ground contact and lifespan guarantee. You get what you pay for, of course.

Another one which has become popular is "Greenheart" which is a tropical specie which since the 1960s is the environmentally passable alternative to creosote ties and pilings. Its a bit expensive but pilings come with 30 year guarantee.

I would tend to the pressure treated as a most cost effective solution - and buy the best guarantee available.

It is possible to buy copper arsenate as a liquid and apply it to joints and cuts. This position used to be filled by "Cuprinol" - but that chemical has now been replaced by "Woodlife Copper-coat" which is like Cuprinol on a diet (EPA) Think the green appearance and smell of your childhood camp building. The Utilities use a product called "Tenex" which is like Cuprinol on steroids for things like crossarms and holes drilled for pole mounts. But you need a permit - and a need - to use this.

Joe K

[BRENT in 10-uh-C]

Thanks Joe. In the shop I use a product called Penetrating Epoxy ( https://www.totalboat.com/products/p...43757091029216 ) that when it is mixed with a little Acetone, it wicks into wood making it very durable and waterproof. Do you think this would make the Ash more prone to Oak-like??

[Joe K]

Originally Posted by BRENT in 10-uh-C

Thanks Joe. In the shop I use a product called Penetrating Epoxy ( https://www.totalboat.com/products/p...43757091029216 ) that when it is mixed with a little Acetone, it wicks into wood making it very durable and waterproof. Do you think this would make the Ash more prone to Oak-like??

That sounds like the WEST system of boatbuilding. Wood-Epoxy Saturation Technique.

I can't say I've ever heard of a WEST boat having rotted out - and for boats the repairs are done via woodwork, and re-saturated after repair. But that may be why "rotted out" is not in the lexicon.

The usual fail for wooden boats is from the "inside out." Particularly where the ribs are "let in" to the keel - the environment is wet continuously, and attention is frequently not paid.

Creosote as a preservative is actually a Nordic technique and this area would be treated generously with creosote during assembly. The Norse "long boats" owe their long life to this - as opposed to the English "galleon" assembly, which counted more on stout oak and mass for strength.

An aside...


Joe K

[Big hammer]

We rebuilt a cooling tower at work, it was made of redwood . The redwood was wet from the water 8 months in the year, the old tower was 50 years old. The 4x4 posts that set in water were basically solid, the outer 1/4 was soft. I would use redwood and not treat it, wood needs to breathe, IMHO

[Seth Swoboda]

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Oak. On every straight truck we've ever owned it's oak and the bed sits on top. It will take decades for it to rot if ever. I've never seen it rot. Treated lumber could cause corrosion of the metal. It's one of those don't over think it items.

[gary678*]

Black Locust is the way to go if you can find it. Naturally rot resistant, no chemical treatment needed. I used it for fence posts and vineyard posts. The below ground part showed only a little deterioration after 25 years, the above ground part was basically 100% intact and I guess would last 50 years or more. Shagbark hickory and oak are also good with oak being the easiest to work of the three. Good luck!

[rotorwrench]

Apitong is used for trailer decking. White oak is also good. I'm not certain what Ford used back in the day since they had many species to pick from up at Iron Mountain. They always painted it black to keep the moisture at bay.

[ronn]

Interesting..........Franklin used ash frames for years on their cars and they held up quite well. Ive always understood ash to be stronger then oak.

[Synchro909]

I'm not familiar with the types of wood mentioned here but I wonder about using the same (I forget the name) plastic type material that we put between the leaves of the springs. There would be no rot and I suspect, no squeaks.

[Keith True]

I think this is being way overthought.This is going to be a shim between the body and frame,strength is not an issue.I installed a lot of bodies in the 80's,we used whatever hardwood was around.Mostly maple and ash.Most of the bodies I installed were running well over 100,000 miles a year in all conditions.The wood would hold up better than the U-bolts in the salt.I think wood is a good idea on a single frame truck.That frame has to flex,and wood allows it to do that without cracking things.If you go overboard on the U-bolts the wood has a little give.

[lrf]

If you go with oak, be sure it is white oak, it has a finer, tight grain whereas red oak is a more open grain letting in moisture. LRF

[nkaminar]

Ash. Paint it with your penetrating epoxy. You already have everything you need.

As an aside, a thin burn on any wood will make it rot resistant. You can see this in old log cabins where the wood has been in ground contact for many years. The charring removes the nutrients that is food for fungus. The charred wood was treated with some kind of oil. Maybe char your ash and then use the penetrating epoxy.

[Model "A" Fords]

Originally Posted by lrf

If you go with oak, be sure it is white oak, it has a finer, tight grain whereas red oak is a more open grain letting in moisture. LRF

White Oaks finer grain is made up of small elongated football shapes that wouldn't accept liquid. Red Oak grain is like a pile of straws running the length of the wood which allows it to suck up lots of liquid.

With these conditions, railway ties made from white oak did not always use protection, where Red Oak had to be Creosoted to last any time in the dampness.

Here is a neet experiment to try with these two woods. Get a straight grained piece of each, size is not fussy. Blow on one end of each with the opposite end in a container of water. Nothing happens with the White Oak but the Red Oak will blow bubbles. I have blown bubbles with a six foot piece of Red Oak.

This is probably more fun than usefull but I couldn't resist.

[Russell Reay]

We moved to a 'new' home in 1958 which was surrounded by big black locust trees. Legend has it that locusts were planted to act as natural lightning rods. In our area locust was the fence post of choice. Dad said it would last 10 years longer than granite.

[Keith True]

A farmer here in town used to say a locust post would last 100 years longer than a stone post.I have them along my stone walls,they were put there before any trees grew up along the fence lines.There are also lines of them in the woods behind me,from when the woods were still fields.All the barbed wire is long rotted away,but the posts are fine.

[ABento]

Terry, I had the local mill size doug fir on a taper from 4 in to 2 ins in 14 ft to fit in between the frame and a 3200 gal water tank on my water truck 30 years ago, its been through hell and back and still good and its exposed to the elements.

[rich b]

We used fir strips under van and stake bodies; then stepped up to oak strips under garbage bodies.

[Terry, NJ]

Locust is the way to go! Thie only thing better is Cypress? (You were expecting me to say Ash wern't you? Not for this!) I'm pausing to reflect on how these qualities of various woods would have been common knowledge in times gone by. Today, Most people don't realize woods have destinct qualities and believe that most woods are pretty much the same.
Terry

[David in San Antonio]

Is locust the same as honey locust? Or what kind are you liking so much?